Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO₂

Abstract

Ammonium type chabazite (NH4CHA) and magnesium type chabazite (MgCHA) was prepared by hydrothermal synthesis and hydrothermal ion exchange. The structure and morphology of ion‐exchanged chabazite was characterized with various experimental techniques such as XRD, SEM, and ICP. The gas adsorption amount of chabazite decreases gradually with increase in temperature or decrease in pressure. The adsorption capacity of NH4CHA to CO2 was 3.33 mmol·g–1 at 273 K, and the saturated adsorption capacity of NH4CHA reached 3.88 mmol·g–1 under extreme pressure. The CO2 molecule was more likely to be adsorbed by all chabazite samples than the N2 molecule due to its linear molecular structure and greater molecular polarity. NH4CHA exhibited larger CO2/N2 selectivity, which first increased and then declined with the temperature decreasing, and reached the maximum value between 400 K to 450 K.

Preparation and Characterization of Chabazite from Construction Waste and Application as an Adsorbent for Methylene Blue

“…Ma prepared zeolite 4A by coal fly ash, the specific surface area and total pore volume of which were 48.36 m 2 g -1 and 0.0910 cm 3 g -1 [25]. Che et al prepared three kinds of chabazite with a Si/Al ratio of 2.2 by hydrothermal synthesis, namely KCHA, MgCHA, and NH 4 CHA, the specific surface area of which was 20.2, 531.9, and 76.6 m 2 g -1 , respectively [26]. Ghasemi et al measured the surface area of coal fly ash, and the corresponding synthesized Na-P1 zeolite under optimized condition was 16.32 and 41.52 m 2 g -1 [27].…”

Modification of Potassium Chabazites Derived from Fly Ash by Dosing Extra Cations: Promoted CO2 Adsorption Capacities and Fine‐Tuned Frameworks

“…The distinct pore system along with the cations endows it interesting properties of pressure‐regulated or temperature‐regulated admission and release of guest molecules . Specifically, a novel adsorption mechanism namely “molecular trapdoor”, apart from traditional equilibrium, kinetic and steric, is observed in CHAs which awards this material dramatical CO 2 selectivity . Therefore, CHAs are acknowledged promising for CO 2 separation.…”